1. Field of the Invention
The present invention relates to retrovirus strains of the HIV-1 group, group O, and in particular the strains called BCF02 (ESS), BCF01 (FAN), BCF06 (LOB), BCF07 (MAN), BCF08B (NKO), BCF11 (NAN) and BCF03 (POC), to fragments of the said retroviruses and to their applications as diagnostic reagent and as immunogenic agent.
2. Description of the Background
Two distinct types of HIV (human immunodeficiency virus: HIV-1 and HIV-2) have been described and are the agents responsible for AIDS. Analysis of their nucleic acid sequence has made it possible to identify various subtypes of HIV-1, although no correlation could be established between variability and pathogenicity. Similarly, HIV-2 exhibits a greater genetic and biological diversity than that previously envisaged.
Analysis of nucleotide fragments of various HIV-1 isolates has shown the existence, through the analysis of the env gene, of at least 7 different subtypes, called A to G (MYERS G. et al., Human retroviruses and AIDS, 1993, Los Alamos Nat. Lab.).
More recently, two other isolates, considered to be considerably more distant from the other 7 subtypes, that is to say whose sequence homology is the most distant from that of the reference HIV-1 strains, have also been isolated: HIV-1ANT70 and HIV-1MVP5180, obtained from Cameroonian patients, and have been attached to a new HIV-1 group, group O, as opposed to group M corresponding to the 7 abovementioned A-G subtypes, taking into account their genomic organization (5' LTR Gag Pol Vif Vpu Vpr Tat Rev Env Nef LTR 3'), (Patent Application WO 89/12094, European Patent Application No. 0,591,914, GuURTLER L. G. et al., J. Virol., 1994, 68, 1581-85).
Analysis of the DNA sequences has shown 65-70% similarity with HIV-1 and 56% with HIV-2.
By using a competition immunoblotting method, using a peptide V3 from MVP5180, a 7-8% prevalence is found in Yaounde. This prevalence might be underestimated since the V3 loop is known, in all the HIV-1 subtypes, to be a highly variable region. Molecular studies also indicate the presence of group O virus in Gabon, France, Spain and Germany.
Ongoing serological studies reveal group O HIV-1 infections in Nigeria, Niger and Senegal.
Knowledge of these various groups and subtypes is particularly important for developing:
reagents for screening for HIV infections which are sufficiently sensitive and specific, that is to say which do not lead to false-negative or false-positive results; and PA1 compositions which protect against all existing subtypes, including the entire group O viruses. PA1 either one of the following sequences, included in the C2V3-env gene fragment (hypervariable loop of gp120): SEQ ID No. 1 (BCF02 (ESS)), SEQ ID No. 2 (BCF08 (NKO)), SEQ ID No. 3 (BCF03 (POC)), SEQ ID No. 4 (BCF06 (LOB)), SEQ ID No. 5 (BCF07 (MAN)), SEQ ID No. 6 (BCF01 (FAN)), SEQ ID No. 7 (BCF11 (NAN)), SEQ ID No. 50 (BCF09), SEQ ID No. 51 (BCF12), SEQ ID No. 52 (BCF13), SEQ ID No. 53 (BCF14), PA1 or one of the following sequences, included in the gp41 fragment of the env gene: SEQ ID No. 8 (BCF02 (ESS)), SEQ ID No. 9 (BCF08 (NKO)), SEQ ID No. 10 (BCF03 (POC)), SEQ ID No. 11 (BCF06 (LOB)), SEQ ID No. 12 (BCF07 (MAN)), SEQ ID No. 13 (BCF01 (FAN)), SEQ ID No. 14 (BCF11 (NAN)), SEQ ID No. 54 (BCF09), SEQ ID No. 55 (BCF12), SEQ ID No. 56 (BCF13), SEQ ID No. 57 (BCF14), PA1 or one of the following sequences, included in the gag gene: SEQ ID No. 15 (BCF02 (ESS)), SEQ ID No. 16 (BCF08 (NKO)), SEQ ID No. 17 (BCF03 (POC)), SEQ ID No. 18 (BCF05 (LOB)), SEQ ID No. 19 (BCF07 (MAN)), SEQ ID No. 20 (BCF01 (FAN)), SEQ ID No. 21 (BCF11 (NAN)), SEQ ID No. 58 (BCF09), SEQ ID No. 59 (BCF12), SEQ ID No. 60 (BCF13), SEQ ID No. 61 (BCF14), PA1 or, if the sequence is not identical to one of the above nucleotide sequences, or is not complementary to one of these sequences, is nonetheless capable of hybridizing with a nucleic sequence derived from a group O HIV-1 virus. PA1 SEQ ID No. 22 (gp41/5'CAM-1): AGRGAAAAAGAGCAGTAGGAT (positions 7800-7821) PA1 SEQ ID No. 23 (gp41/5'CAM-2): TCTAAGTGCAGCAGGTAGCACTAT (positions 7843-7866) PA1 SEQ ID No. 24 (gp41/3'CAM-2): CTAAGTTGCTCAAGAGTGGTA (positions 8594-8573) PA1 SEQ ID No. 25 (gp41/3'CAM-1): GTTGCTCAAGAGGTGGTAAGT (positions 8590-8570) PA1 a step of extracting the nucleic acid to be detected, belonging to the genome of the HIV-1 type virus, which may be present in the biological sample and, where appropriate, a step of treating the nucleic acid with the aid of a reverse transcriptase, if the latter is in RNA form, PA1 at least one cycle comprising the steps of denaturation of the nucleic acid, annealing with at least one sequence in accordance with the invention and extension of the hybrid formed, in the presence of the appropriate reagents (polymerizing agent such as DNA polymerase and dNTP), and PA1 a step of detecting the possible presence of the nucleic acid belonging to the genome of a group O HIV-1 type virus (group specificity). PA1 those expressed by the C2V3-env gene fragment in accordance with the invention: SEQ ID No. 26 (BCF02 (ESS)), SEQ ID No. 27 (BCF01 (FAN)), SEQ ID No. 28 (BCF01 (FAN)), SEQ ID No. 29 (BCF06 (LOB)), SEQ ID No. 30 (BCF07 (MAN)), SEQ ID No. 31 (BCF11 (NAN)), SEQ ID No. 32 (BCF08 (NKO)), SEQ ID No. 33 (BCF08 (NKO)), SEQ ID No. 34 (BCF03 (POC)), SEQ ID No. 35 (BCF03 (POC)), SEQ ID No. 62 (BCF09), SEQ ID No. 63 (BCF12), SEQ ID No. 64 (BCF13), SEQ ID No. 65 (BCF14), PA1 those expressed by the gp41env gene fragment in accordance with the invention: SEQ ID No. 36 (BCF02 (ESS)), SEQ ID No. 37 (BCF01 (FAN)), SEQ ID No. 38 (BCF06 (LOB)), SEQ ID No. 39 (BCF07 (MAN)), SEQ ID No. 40 (BCF08 (NKO)), SEQ ID No. 41 (BCF03 (POC)), SEQ ID No. 42 (BCF11 (NAN)), SEQ ID No. 66 (BCF09), SEQ ID No. 67 (BCF12), SEQ ID No. 68 (BCF13), SEQ ID No. 69 (BCF14), PA1 those expressed by the gag gene fragment in accordance with the invention: SEQ ID No. 43 (BCF02 (ESS)), SEQ ID No. 44 (BCF01 (FAN)), SEQ ID No. 45 (BCF06 (LOB)), SEQ ID No. 46 (BCF07 MAN)), SEQ ID No. 47 (BCF11 (NAN)), SEQ ID No. 48 (BCF08 (NKO)), SEQ ID No. 49 (BCF03 (POC)), SEQ ID No. 70 (BCF09), SEQ ID No. 71 (BCF12), SEQ ID No. 72 (BCF13), SEQ ID No. 73 (BCF14).
Indeed, it has been shown, in particular, that some detection reagents were not sufficiently sensitive and did not always make it possible to detect group O HIV-1 infections (LOUSSERT-AJAKA I. et al., Lancet, 1994, 343, 1393-94), which has led to the withdrawal of three screening kits and to the declassification of two others on the French market.
The results show that the group O viruses are very distant from the group M HIV-1 subtypes. These results indicate that the HIV-1 viruses ought to be classified in two different groups, namely: HIV-1 M and HIV-1 O. The group O viruses appear to be capable of being transmitted by horizontal and vertical routes, leading to a very wide distribution of this infection. The pathogenicity of these viruses is under study. The divergence of these viruses should be taken into account in the sensitivity of diagnostic tests and in the development of vaccines.